BUFFALO SOCIETY OF NATURAL SCIENCES 



6 9 



along all coasts even where no rivers enter as well as at considerable 

 distances from shore beyond the debouchures. 



Walther makes mention of the occurrence of great rafts of trees 

 off the mouth of the Congo, 450 km. from shore, some of these inter- 

 locking tree islands being 100 m. across. Agassiz likewise has 

 noted in the Caribbean Sea, Helix, leaves, and other land organisms 

 dredged from a depth of 1000 to 2000 fathoms, which is far beyond 

 the littoral zone. 



Thus we must conclude that in the marine waters, and especially 

 in the littoral zone, there is not only an abundance of invertebrate 

 organisms of nearly all phyla, but there are stragglers from other 

 realms; insects and plants are blown out to sea, while terrestrial ani- 

 mals and vegetal remains, together with fluviatile organisms, are 

 carried along by the rivers, all at length being entombed in the ma- 

 rine sediments with the hard parts of the organisms which lived and 

 died in the sea. In such cases we should expect to find the fluviatile 

 and terrestrial remains shattered and worn on account of being trans- 

 ported oftentimes for a considerable distance, and usually subject to 

 partial destruction by the debris which the rivers carry. At any rate, 

 it is apparent that it is customary, not anomalous, for the remains 

 of terrestrial and marine organisms to occur together. 



Fresh Water. The fresh- water faunas of rivers and lakes, on 

 the other hand, present quite different features. While the number 

 of individuals in a given river or lake may indeed be large, the num- 

 ber of genera and species is very small as compared with those in the 

 neighboring marine waters. Furthermore, there are only a few large 

 classes abundantly represented, such as the fish, molluscs, and pro- 

 tozoa, while all of the other classes, so well represented in marine 

 waters, are in given rivers or lakes represented often by a single spe- 

 cies only, or by none at all. Three comparative sets of figures for 

 the molluscs will serve to illustrate how small the number of genera 

 and species is in fresh water when compared with those in marine 

 waters at approximately the same latitude. 



Table showing number of Genera and Species of Mollusca in Various Bionomic Realms 



LOCALITY 



NIAGARA 



SAGINAW 



WOODS HOLE, 



RIVER 



BAY 



MASS. 



permille 



permille 



permille 



O.134 



0.105 



30.0 



iS 



23 



133 



24 



93 



203 



MASS. 

 COAST 



Salinity 

 Genera. 

 Species . 



permille 

 35-o 



175 

 466 



